Seal Band Pretinning and Cap Sealing Without Chemical Flux
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Fluxless pretinning and sealing of hermetic caps to substrate-carrying chips are performed in a clean hydrogen gas atmosphere at low temperatures of 220-250ŒC using lead preforms encapsulated with Sn, instead of eutectic solder. Referring to the drawing which is an exploded sectional view, a solder preform 12 is joined to a seal band pad 11 on the periphery of a substrate 10 carrying chips 15 to be enclosed hermetically by cap 13. The preform 12 is joined to the pad either during the pin-brazing operation, or thereafter, in an atmosphere of clean hydrogen gas 20. Gas 20 is supplied to the confined space 21 within a belt furnace or a chamber 19 housing the substrate 10 during the joining operation.